1. Field of the Invention
The invention relates to automatic drive transmissions. In particular, the invention relates to an automatic drive in which the gear ratio changes automatically as the speed of a driven shaft increases and which has the characteristic that the driven shaft is free to continue rotating when the driving gears are retarded or stopped in their rotation.
2. Prior Art
Automatic transmissions known to the prior art generally comprise a first driven shaft which is connected to a prime mover. There is a second shaft, in parallel relationship to the first shaft. This second shaft is the shaft from which power is taken and provided to wheels or other equipment. In general, a series of gears are affixed to the driven shaft and these gears have varying diameters. A similar set of gears is freely coupled to the second shaft and these gears have complimentary diameters to the gears on the driven shaft such that they are capable of mating with the gears on the driven shaft and the shafts remain parallel. The effect is to provide a differing set of gear ratios available when coupling drive power from the first shaft to the second.
As noted, the gears coupled to the second shaft are freely coupled thereto so that, although restrained to remain meshed with the gears on the first shaft, the second shaft may rotate freely within these gears without driving the gears or being driven by them. Typically, a clutching arrangement is used to couple one of these gears in a driving relationship with the second shaft. By choosing which of the series of gears is clutch-coupled to the second or output shaft the gear ratio between the first shaft, coupled to the primary driving force, and the second shaft, providing the output power, is determined.
The present invention will differ from the prior art in several ways. For instance, the primary motor force will be coupled directly to a first drive gear which will in turn be coupled to a drive shaft and the coupling between the first drive gear and the drive shaft will be maintained only until the drive shaft is otherwise driven on a selected greater speed. The same drive gear which initially drives the drive shaft will also provide the motive force to drive a drive transfer shaft from which driving force will be transferred to the drive shaft in varying gear ratios depending upon the speed of rotation of the drive shaft.